What is the modulation index of an FM phone transmitter producing an instantaneous carrier deviation of 6 kHz when modulated with a 2 kHz modulating frequency?

The modulation index for an FM phone transmitter is the ratio of the instantaneous frequency deviation to the frequency of the modulating audio signal. This ratio helps determine the bandwidth and the distribution of energy in the FM signal's sidebands. To find the modulation index, simply use the formula: Modulation Index = Deviation ÷ Modulating Frequency. For this specific transmitter, the instantaneous carrier deviation is 6 kHz and the modulating frequency is 2 kHz. By dividing 6 kHz by 2 kHz, you get a modulation index of 3.